dual electric fan
Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=114321
Printed Date: April 28, 2024 at 6:28 PM
Topic: dual electric fan
Posted By: ga_goosh
Subject: dual electric fan
Date Posted: June 08, 2009 at 7:25 PM
i have a car that does not originally have electric fans, and the ac has been removed. i have found a way to install a temp switch on the radiator from a different car. i found an e-fan that has 2 fans and cover the radiator completely. i want it to run in a series curcuit for low noise output but to switch to parallel circuit if it needs more coolong power. will i need 2 thermo switches rated at different temps? is there a temp switch that has dual temp switches in 1? i also dont know how to run the relays to obtain this. can i get a scematic of something like this? thanks for any help offered :D
Replies:
Posted By: i am an idiot
Date Posted: June 08, 2009 at 7:39 PM
Have you wired the fans in series yet to see if they turn fast enough to do any good?  Amplifier Output = Battery and ground. Voice Coil one = fan 1 Voice coil two = fan 2 Negative trigger from switch = output of highest temperature sensor. You will have to wire another relay to the other temp sensor that will apply power to the 2 relays when the temp trips that sensor. Let me know if you need a pic of that too.
Posted By: ga_goosh
Date Posted: June 08, 2009 at 8:00 PM
i am an idiot wrote:
Have you wired the fans in series yet to see if they turn fast enough to do any good?
no i havent checked yet i will need to see if it is even enough to work. the fans are coming off of a MR2 84-89. i am not sure but it might do this for the ac fan in stock form. i will have to check i am an idiot wrote:
You will have to wire another relay to the other temp sensor that will apply power to the 2 relays when the temp trips that sensor. Let me know if you need a pic of that too.
yes i will need a pic of that too thanks also is the fan switch in this scematic normally open or closed? i forgot to mention this but the temp switch that is coming from the doner car is a 1 wire switch to ground that is normaly grounded and opens when it is at temp. but i can source one that has 2 wires and is normally open. for ease of wiring. thanks
Posted By: i am an idiot
Date Posted: June 08, 2009 at 8:11 PM
Ideally you could use a one wire sensor that is open at low temp and would close when target temp is reached. With that type of switch, the posted diagram will work. If you can not find a switch like that, I can modify it to make it work. 
Posted By: ga_goosh
Date Posted: June 08, 2009 at 8:34 PM
i am an idiot wrote:
Ideally you could use a one wire sensor that is open at low temp and would close when target temp is reached. With that type of switch, the posted diagram will work. If you can not find a switch like that, I can modify it to make it work.
wouldnt it be on in series all the time that way, and parallel when target temp is achieved (if it ever gets there) meaning the fans will always be on if the car is on? i would like it to turn off if the engine is at or below running temp. as for the switch i dont know exactly what switch to get yet. i do know it comes from a hyundi tho. if you can modify for the origional switch that would be great. i am not opposed to using 2 thermo switches rated at different temps. lets say one at 190 and the other at 210
Posted By: i am an idiot
Date Posted: June 08, 2009 at 8:46 PM
The second diagram kills power to the entire first diagram. The 2 relays of the first diagram will not get any power until the second diagram feeds power to them. I will modify the top pic tomorrow.
Posted By: ga_goosh
Date Posted: June 08, 2009 at 8:59 PM
is this how it is supposed to go? 
Posted By: i am an idiot
Date Posted: June 08, 2009 at 9:13 PM
Yes that is how it is supposed to go. Only thing is, it will pull near 30 amps of current. You may not want to power this with an ignition circuit.
Posted By: ga_goosh
Date Posted: June 08, 2009 at 9:18 PM
ok so then i can use a standard 4 pole normally open relay so it will be switched by ignition?
Posted By: i am an idiot
Date Posted: June 08, 2009 at 9:24 PM
Correct. The 2 relays at top of the pic need to be 5 pole. The other 2 can be of the 4 pole type. Pole = connections Do not go asking for a 4 pole relay. It will have way too many connections.
Posted By: ga_goosh
Date Posted: June 08, 2009 at 9:29 PM
would this keep everything safe? 
Posted By: i am an idiot
Date Posted: June 08, 2009 at 9:52 PM
You have the ignition and the battery confused on the newest relay.
Howie, I didn't do it.
Posted By: ga_goosh
Date Posted: June 08, 2009 at 9:57 PM
well i dont know which conection is which. i was refering to a normally open 4 connection relay that will close on ignition for the 30 a fused wire
Posted By: ga_goosh
Date Posted: June 08, 2009 at 10:04 PM
Posted By: ga_goosh
Date Posted: June 08, 2009 at 10:06 PM
yea howie it was me lol
Posted By: i am an idiot
Date Posted: June 08, 2009 at 10:34 PM
Notice the Position of the vertical and horizontal lines of the relays. Howie is a real stickler for terminal 85 being ground. You used 86 as ground. I corrected that too.
Posted By: ga_goosh
Date Posted: June 09, 2009 at 4:31 PM
ok cool thanks. also does this even need to be switched by ignition since it will all turn off when the engine cools off or will a relay be on all the time and wear out faster or any thing else like that? thanks
Posted By: i am an idiot
Date Posted: June 09, 2009 at 8:45 PM
As long as the temp is below the temp of the lowest temp sensor, there will be Zero current draw. Battery would be better and one less relay.
Posted By: ga_goosh
Date Posted: June 09, 2009 at 8:48 PM
ok thank you for all your help. you sir are very knowlegable in the electric field.  kudos to you
Posted By: dualsport
Date Posted: June 09, 2009 at 9:30 PM
You could also do without the relay and still have it switch off with the ignition by just connecting the ign switched to the coil of the relays. The main current source can be connected to your fused constant battery source, as it should be. The ignition line will just be used for the relay switching so there's no problem with overdrawing from it.
Posted By: i am an idiot
Date Posted: June 09, 2009 at 10:08 PM
Very good point.
Posted By: dualsport
Date Posted: June 09, 2009 at 10:25 PM
What happened to Photobucket, did someone tip it over?
Good thing you uploaded the latest drawing to the local server- 
Posted By: ga_goosh
Date Posted: June 10, 2009 at 2:33 PM
dualsport wrote:
What happened to Photobucket, did someone tip it over?
Good thing you uploaded the latest drawing to the local server-
so are you saying where the fused 12v+ is coming into the top right relay i can hook up a fused IGN instead of it turning off after the car cools? also if it doesnt draw any power when the engine is cool then it might work better that way since when i turn off the car and the fans are on then it will continue to cool until the engine has dropped below the thresh hold of the temp switches yea i have edited it a couple of times. here it is in the final with ignition on a seperate relay 
no ignition 
Posted By: ga_goosh
Date Posted: June 10, 2009 at 2:47 PM
is this where you are talking about introducing IGN to the diagram? 
Posted By: i am an idiot
Date Posted: June 10, 2009 at 2:59 PM
Posted By: ga_goosh
Date Posted: June 10, 2009 at 3:14 PM
ok cool thanks : )
Posted By: dualsport
Date Posted: June 10, 2009 at 8:18 PM
Well, if you really want the fans to continue running even after you shut off the ignition, then you shouldn't use the ignition switch line- in that case you'll want it all to be constant power, and rely on the thermo switches to shut everything off properly. I'd go with the ignition switched setup myself, bit safer that way. Fan switches have been known to stick on, though OEMs do use the non ignition switched setup, so they must be confident enough on their reliability. With the ign switched setup, if you really want to have the engine cool after a hot run, then just let the engine idle for a while before you shut down. Also, you might want to use the switched ignition for the upper relays also, since the relays can't do anything without primary power coming from the bottom relay anyway. Another bit of safety in case your fan switches fail and leave the relays energized while parked. Not as bad as the fans running, but the relay coils can also drain down the battery after a while.
Posted By: ga_goosh
Date Posted: June 11, 2009 at 3:31 PM
dualsport wrote:
Well, if you really want the fans to continue running even after you shut off the ignition, then you shouldn't use the ignition switch line- in that case you'll want it all to be constant power, and rely on the thermo switches to shut everything off properly. I'd go with the ignition switched setup myself, bit safer that way. Fan switches have been known to stick on, though OEMs do use the non ignition switched setup, so they must be confident enough on their reliability. With the ign switched setup, if you really want to have the engine cool after a hot run, then just let the engine idle for a while before you shut down. Also, you might want to use the switched ignition for the upper relays also, since the relays can't do anything without primary power coming from the bottom relay anyway. Another bit of safety in case your fan switches fail and leave the relays energized while parked. Not as bad as the fans running, but the relay coils can also drain down the battery after a while.
ok you make a good point. that is the original reason i wanted ignition switched because i didnt want to have to worry about an activated relay doing nothing while ther car was off. i will use ignition especially since the OEM temp switched wont work in my case (they are open at temp normally closed) plus i just dont want to use that many relays for a fan set up. if i wanted to cool the engine off after a hot run then i can have the car on engine off untill the radiator cools off enough then i can just restart and go. i am happy with this set up i am going to try it out soon. i just have to get the proper thermo switches. i found one on summit racing that turned on at 185 and turned off at 170. i will yse this one for the low speed. for the high speed i will try a 195 on not sure what the off is hopefully it is off at 185 lol
Posted By: ga_goosh
Date Posted: June 18, 2009 at 2:44 PM
ok with this set up how hard would it be to hook ac up to this and have it function the same?
Posted By: ga_goosh
Date Posted: June 18, 2009 at 2:45 PM
is it as simple as changing the low temp thermo switch to an a/c power?
Posted By: dualsport
Date Posted: June 18, 2009 at 6:04 PM
Do you mean ac as in air conditioning as opposed to alternating current? You want to switch on the fans automatically when you turn the air conditioning on? Are you looking to switch it based on the compressor kicking on only, or on all the time you turn the A/C on?
Posted By: ga_goosh
Date Posted: June 19, 2009 at 7:30 PM
a/c as in air conditioning. and yes when ever the a?c is on then the fans will be on in slow speed. if it makes the engine get hot then the temp switch will turn them on in high speed. will this do it? 
Posted By: dualsport
Date Posted: June 19, 2009 at 8:35 PM
So you won't need the fans at all if your A/C happens to be turned off?
Or do you plan to have the A/C on all the time?
Posted By: i am an idiot
Date Posted: June 19, 2009 at 9:29 PM
Your pic will not work. Do you want the fans to come on high or low when the air is on?
Posted By: dualsport
Date Posted: June 19, 2009 at 10:20 PM
I'll assume you don't want to have to turn the A/C on in order for the fans to run, and that your A/C control line is ground switched.
With those assumptions, you can just wire it like this-
Turning on the A/C will turn the fans on in low serial connected mode, and also turns them on low when the lower 190 degree switch closes.
If the high temp switch closes, the fans will be connected in full power parallel mode.
With the ignition off, the fans will remain off regardless of the thermo switch states.
Posted By: i am an idiot
Date Posted: June 20, 2009 at 3:59 AM
I think the A/C compressor wire will be a positive wire. I have not went back to see what kind of car we are dealing with, but if the compressor has a switched positive wire, let me know.
Posted By: dualsport
Date Posted: June 20, 2009 at 6:49 AM
Yeah, I'm not sure what he was planning on picking up for the A/C control input, but since his/her diagram indicates it's a ground switched control, I went with that. Either the compressor control or the main A/C switch could be used, Advantages and drawbacks to either method I guess. If the compressor control is used, the fans will be switching on and off continuously as it cycles the compressor. Normally that'd be harder on the relays with all the extra switching, but since it's the low power mode it might not be so bad. Maybe he/she was planniing on using the control switch for the A/C itself, with a ground-when-on output. Either way, that's what I had to assume was being used for the control, since his/her diagram wouldn't have worked if it was high switched.
Posted By: Mad Scientists
Date Posted: June 20, 2009 at 6:22 PM
My suggestion for the A/C would be to have the fans on HIGH whenever there's a call for A/C. Engine heat isn't the reason for fans ON with A/C ON.. it's A/C high side pressure. Some of the newer cars sense this to determine when to turn the fans on during A/C operation. Lack of airflow across the condensor on a hot day with the A/C on will spike pressures and unpleasant $BIGNUM damage may result. Jim
Posted By: dualsport
Date Posted: June 20, 2009 at 8:30 PM
The original post says the A/C has been removed; is that still the case or has it been unremoved?
Posted By: Mad Scientists
Date Posted: June 21, 2009 at 5:44 AM
On June 18 the OP asked.. "ok with this set up how hard would it be to hook ac up to this and have it function the same?" <shrug> I dunno.. Jim
Posted By: ga_goosh
Date Posted: June 22, 2009 at 10:02 PM
yea the a/c is still deleted and it will not ever be put back on while i am the owner. the car is a 1986 toyota corolla ae86 by the way. i have all ready got the wiring diagram i need for my dual fan set up thanks to i am an idiot and dualsport. i am also wanting to learn something from all of this. so i figured why not just learn something for future reference. i know all the new cars with a/c and e fans do this to save on noise output from the fans. so my question is if i was to eliminate the lower of the 2 temp switches and added a signal from the a/c at the same place would it still work in dual speed mode? as when the a/c is on it will be in low speed and if the cooland temp reaches 200 then it will switch over to high speed. and if the a/c os off will it only work in high speed since the a/c signal is not present? thanks for all the help sorry i have not been able to get on in a few days
Posted By: i am an idiot
Date Posted: June 22, 2009 at 10:17 PM
It would be easy enough to do whichever way you want. To have it come on with both, it will simply require another relay and a diode. The relay would be to convert the positive AC compressor feed to a negative signal to trigger the relay. The diode isolates the AC relay from the temp sensor.
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